Burglar-alarm



(No Model.)

G. H. HODGKI NS. BURGLAR ALARM.

No. 429,762. Patented June 10, 1890.

UNITED STATES PATENT OFFICE.

GEORGE HERVEY HODGKINS, OF PEABODY, MASSACHUSETTS.

BURGLAR-ALARM.

SPECIFICATION forming part of Letters Patent No. 429,762, dated June 10, 1890.

Application filed August 5, 1889. Serial No. 319 ,814- (No model.)

To all whom it may concern.-

Be it known that I, GEORGE HERVEY Honc- KINS, of Peabody, in the count-y of Essex and Commonwealth of Massachusetts, have invented certain new and useful Improvements in Burglar-Alarms; and I do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanyingdrawings, and to letters of reference marked thereon, which form a part of this specification.

My invention relates to that class of burglaralarms which are adapted to be sounded by the release of mechanism caused by the opening of a door or window.

My improvements consist in having in connection with the ordinary clock-work-alarm mechanism a sliding spring-bar for bearing against the arm of the striking-hammer when pulled out against the action of its spring, and thus lock the hammer-arm, and also when said baris released and it has been slid back by its spring out of engagement with the hammerarm the latterwill be unlocked and the hammer will be free to strike; and my improvements consist, also, in certain details of construction, as more particularly hereinafter described.

In the accompanying drawings, Figure 1 illustrates a perspective view of my improved alarm as applied to a door. Fig. 2 illustrates a side elevation enlarged with one side of the casing broken away. Figs. 3 and 4 illustrate details. Fig. 5 is a perspective View of a modification as applied to a door or window. Fig. 6 is an end View of the same, and Figs. '7 and 8 are details of the modification shown in Figs. 5 and 6.

Similar letters represent similar parts in all of the figures.

A is the box or casing of an ordinary clockwork alarm, and B is the escapement wheel or ratchet, which is connected with the mainspring a in the ordinary manner by intermediate gearing-as, for example, that shown in Fig. 2, the pinion iron the ratchet-shaft c engaging with the gear don the spring-shaft e.

C is the hammer-arm fixed to the rock-shaft f, and having the hammer g at its upper end, and D is the oscillating escapement-dog secured to the shaft f and adapted to engage with the escapement-wheel B.

E is a bar suspended in suitable guideways longitudinally in the casing A, one end of which has a transverse right-angled arm h extending back of the hammer-arm C,while the other end extends through and beyond the casing.

Extending back of the casing A, from an upright F, secured to the same, are two wedgeshaped arms G H, the upper one H being pivoted near its forward end to the arm G, which is firmly attached to the upright F. A chain or cord c connects the upper arm H with the forward end of the bar E, passing over and guided by suitable pulleys is Z. hen the arm H is drawn down against the arm G, as shown in Fig. 1 and in dotted lines in Fig. 2,

it will, through the chain or cord i, pull out ihe' bar E, and the arm h will be drawn against the hammer-arm C, so that the dog D will be in fixed engagement with the escapementwheel. B. A coil tension-sprin g m encircles the front end of the bar E, and is retained in position by the front wall of the casing and a collar or on said bar E. This spring tends constantly to force the bar E back and its arm it out of contact with the hammer-arm C, so as to allow the ratchet-wheel B to cause the dog D, and thereby the hammer-arm C, to oscillate. This action of the spring on also, by means of the chain 11, raises the arm H.

When the alarm is to be applied to a door, it may be suspended from the door-knob by a chain. The arm H is drawn down against the arm G, and the two arms G and H are then forced into the crack between the door A and its'frame B. (See Fig. 1.) The bindingcontact of the door-frame and door against the arms will retain them in position with the arm H against the arm G, and the arm h of the bar E against the hammer-arm (l,locking the latter. The mainspring a is wound up by the handle 0 on the shaft 6, and said spring will be locked or prevented from unwinding by the aforesaid locking mechanism, which is retained in lock by the binding-contact of the door and the door-frame, as aforesaid. Then when the door is opened the arm H will be released and the spring or will force the bar E and its arm it out of contact with the ham- 'mer-arm C, thus releasing the dog D from the ratchet 13, unlocking the same and allowing the mainspring a to unwind, when the rotation of the ratchet B will cause the oscillation of the dog D and the hammer-arm (1, so as to strike the bell.

The outer portion 1) of the shank of the handle 0, by which the mainspringais wound, may have two plane parallel sides, and a flat piece of metal q, having a mortise "r in one of its ends and a handle-knob near its other end, may serve as a key to lock the shaft 6 and the mainspring a by themortiser, fitting over the plane sides of the shank p. A dovetailed guide 3 is fixed to the casing A, in which slides the piece g.

In place of the two arms G II (shown in Fig. 5) and the support F, the pulleys k Z and chain '1 a lever or trigger K, having a lateral pin 13 near its upper end and a curved arm U extending from its lower end, maybe pivoted to the casing A below the bar E. The pin 25 is adapted to enter a hole o in the arm E when the latter has been drawn out so as to lock the hammer-arm G. Then when the pin 1, is withdrawn from the hole 1' the hammerarm 0 will be released and the alarm will strike. The alarm is adapted to be attached to the frame of the door or window, so that the opening of the door or window will cause the latter to bear against the curved part to of the trigger K and release the pin tfrom the hole n in the bar E.

Fig. 1 shows the alarm as applied to a doorframe, A being the door and B the frame.

A very convenient way of attaching the casing to the door or window frame is by means of a dovetailed mortise-socket, Fig. 7, to be secured to the frame, and a projecting lug or tenon, Fig. 8, secured to the casing A.

hat I claim as my invention is 1. In a burglar-alarm, the combination of the oscillating hammer-arm and means for oscillating the same, two wedge-shaped arms for entering the crack between a door or window and its frame, or between the two sashes of a window, one of said arms being pivotally connected and the other arm being rigid, a spring-lock for bearing against the hammer-arm to prevent its oscillation, and a cord or chain connecting said lock with the pivotal wedge-shaped arm for holding said lock against the hammer or for releasing the same, all as set forth.

2. In a burglar-alarm, the combination of the oscillating hammer-arm and means for oscillating the same, the spring-bar E, having the lateral arm h for bearing 'against the hammer-arm, a chain or cord 1', attached to the outer end of the bar E, the wedge-shaped arms G II, the pivotal arm ll being attached to the chain or cord 2', and guides for said chain or cord between the bar E and the arm II, all as set forth.

3. In combination with the shaft 6 of the mainspring and the handle 0 for attachment to said shaft and for turning the same, and having the shank p with the parallel plane faces, the mortised piece q,with its mortise 'r, for fitting over the plane faces of the shank to lock the same, the shank a and the mainspring a, all as set forth.

GEORGE HERVEY HOD GKINS.

Witnesses:

HAYES LoUcEE, .ToHN MURRAY MARSHALL. 

